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Publications

Publications by CRIIS

2016

Pollen-based predictive modelling of wine production: application to an arid region

Authors
Cunha, M; Ribeiro, H; Abreu, I;

Publication
EUROPEAN JOURNAL OF AGRONOMY

Abstract
A wine forecast model for one of the most arid wine regions of the Europe-Alentejo was improved and tested for the period 1998-2014. During this period, Alentejo region had strong upward trends in wine production associated to the increase of vineyard area. The forecast model was supported on a hierarchical analysis, including the determination of the potential production at flowering by quantifying airborne pollen concentration, followed by a climate based evaluation of the possible impact of fruit-set conditions in the limitation of production. Through the monitoring of airborne pollen flows it is possible to define an accurate main pollen season and determine the regional pollen index that will be used as independent variable in the regional forecast model. The time trend, which was initially removed from data, was then added back to obtain the forecast. Stepwise regression and cross-validation were employed during the period 1998-2014 for calibration of the model used for predicting annual wine production. The developed model explained about 86% of wine variance over the years with absolute average error of 6% for the cross validation and 87% of cases had differences between actual and forecasted wine production below 10%. The reliability and early-indication ability of the proposed forecast model justify their use to respond to a number of government agencies and wine industry concerns and activities.

2016

Comparison of harvest-related removal of aboveground biomass, carbon and nutrients in pedunculate oak stands and in fast-growing tree stands in NW Spain

Authors
Gomez Garcia, E; Dieguez Aranda, U; Cunha, M; Rodriguez Soalleiro, R;

Publication
FOREST ECOLOGY AND MANAGEMENT

Abstract
In northern Spain, the use of biomass to produce bioenergy has led to increased exploitation of both natural pedunculate oak (Quercus robur L.) stands and fast-growing plantations of natural or exotic species. In this study, we developed a model for estimating aboveground biomass, carbon and nutrient contents in different pedunculate oak components at individual-tree and at stand level. Six harvesting methods were simulated in an average stand, ranging from whole-tree to stem wood extraction (stem without bark) and including the conventional harvesting method used in the region (extraction of stem plus branches of diameter >7 cm). The biomass and macronutrients extracted were compared with those removed during harvesting of fast-growing tree species (Eucalyptus globulus Labill., Pinus radiata D. Don and Pinus pinaster Ait.) on the same temporal basis (mean annual values). Harvesting pedunculate oak stands generally extracted lower amounts of nutrients than harvesting fast-growing species, although the differences depended on the species, macronutrients and harvesting regime considered.

2016

An optical fiber sensor and its application in UAVs for current measurements

Authors
Delgado, FS; Carvalho, JP; Coelho, TVN; Dos Santos, AB;

Publication
Sensors (Switzerland)

Abstract
In this paper, we propose and experimentally investigate an optical sensor based on a novel combination of a long-period fiber grating (LPFG) with a permanent magnet to measure electrical current in unmanned aerial vehicles (UAVs). The proposed device uses a neodymium magnet attached to the grating structure, which suffers from an electromagnetic force produced when the current flows in the wire of the UAV engine. Therefore, it causes deformation on the sensor and thus, different shifts occur in the resonant bands of the transmission spectrum of the LPFG. Finally, the results show that it is possible to monitor electrical current throughout the entire operating range of the UAV engine from 0 A to 10 A in an effective and practical way with good linearity, reliability and response time, which are desirable characteristics in electrical current sensing. © 2016 by the authors; licensee MDPI, Basel, Switzerland.

2016

Chemometric analysis on free amino acids and proximate compositional data for selecting cowpea (Vigna unguiculata L.) diversity

Authors
Domínguez-Perles, R; Machado, N; Abraão, AS; Carnide, V; Ferreira, L; Rodrigues, M; Rosa, EA; Barros, AI;

Publication
Journal of Food Composition and Analysis

Abstract

2016

Chemometric analysis on free amino acids and proximate compositional data for selecting cowpea (Vigna unguiculata L.) diversity

Authors
Dominguez Perles, R; Machado, N; Abraao, AS; Carnide, V; Ferreira, L; Rodrigues, M; Rosa, EADS; Barros, AIRNA;

Publication
JOURNAL OF FOOD COMPOSITION AND ANALYSIS

Abstract
Biodiversity of cowpea, along with the interesting agricultural and nutritional properties, has encouraged research with local landraces of Portugal. This work deals with the composition of dry beans of cowpea from 28 different Portuguese cultivars concerning dry matter (DM), crude proteins (CP), fat content (FC), ash, and concentration of free essential and non-essential amino acids. Data obtained on these traits showed contents of DM, FC, ash, and CP in the ranges of 95.7-98.9%, 1.0-1.6%, 2.7-4.7%, and 18.6-26.9%, respectively. The content in free amino acids was evaluated as an indicator of germinating potential of the diverse cultivars assessed. The amino acids content was the highest in the varieties 'Vg50' and 'Vg58'. Cluster and principal component analyses of the data allowed the identification of the most promising Portuguese landraces of cowpea to be used for breeding new varieties with improved germination potential and nutritional traits.

2016

Effect of Agro-Environmental Factors on the Mineral Content of Olive Oils: Categorization of the Three Major Portuguese Cultivars

Authors
Gouvinhas, I; Dominguez Perles, R; Machado, N; Carvalho, T; Matos, C; Barros, AIRNA;

Publication
JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY

Abstract
The nutritional properties and safety of olive oil are strongly dependent on the content of mineral nutrients and trace elements. Hence, this work assesses the content for quality and toxic metals of olive oils from three major Portuguese cultivars ('Galega', 'Cobran double dagger osa' and 'Picual') obtained from olives in different ripening stages. This evaluation was achieved by flame atomic spectrometry and atomic absorption in a graphite furnace, depending on the metal to be analysed. The results showed mean concentrations of the mineral nutrients Ca and Mg of 20.00 A mu g g(-1), and K and Na of 40.00 and 170.00 A mu g g(-1), respectively, while the trace elements Fe, Co, Cu, Mn, Zn and Ni had mean values of 0.53, a parts per thousand currency sign 0.01, 0.33, 0.10, 1.09 and 0.64 A mu g g(-1), respectively. The mean content of the toxic metals Al, Cd, Pb and As were 27.46, 0.03, 0.09 and 0.36 A mu g g(-1), respectively, which were according to the values proposed by European regulations. The evaluation of the data obtained by partial least square regression allowed the identification of the minerals with the strongest potential to discriminate between the season (Na, Cu, Zn and Ni) and the cultivar employed in the olive oil performance (Fe and Mn).

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